1. Field of the Invention
The present invention relates to a hydraulic power steering apparatus suitable for use in automobiles and the like, and more particularly, it relates to the improvement of a hydraulic power steering apparatus described in the co-pending U.S. application Ser. No. 08/138,963 of the same assignee as this application.
2. Discussion of Related Art
In a conventional power steering apparatus, center-open type variable orifices arranged in a rotary control valve operate immediately to supply the pressurized fluid to one of power cylinder chambers and to exhaust the fluid from the other power cylinder chamber even when a steering wheel is turned slightly from the neutral position. This causes the differential pressure across a power cylinder to begin to increase immediately and to increase more gradually as the rotational angle of the rotary control valve further increases. Accordingly, the conventional power steering apparatus does not give the driver a steady steering feeling at around the neutral position.